Counter stacker

ABSTRACT

An article stacker including a movable elevator upon which articles may be stacked, stack transfer means adapted following predetermined descent of the elevator to intercept and remove a completed stack from the elevator to enable the completed stack to be ejected from the stacker and the elevator reset for the next stack, stack ejector means adapted when actuated to move the completed stack along the stack transfer means and out of the stacker, and control means for the elevator and the ejector means adapted to lower the elevator as a stack builds up thereon, and, following transfer of the completed stack from the elevator to the transfer means, to actuate the ejector means to remove the completed stack, the control means including means to quickly return the elevator to the stack-start position following ejection of the completed stack from the stacker.

0 United States Patent [111 3,630,517

[72] Inventor Albert G.Ensltnt 2,991,999 7/196] Doemer 271/86 21 A l N Primary Examiner-Joseph Wegbreit I 1 Attorneys-James J. Ralabate, Norman E. Schrader and [22] Fued 1970 Frederick E. McMullen [4S] Patented Dec. 28, 1971 [73] Assignee Xerox Corporation Rochester ABSTRACT: An article stacker including a movable elevator upon which articles may be stacked, stack transfer means adapted following predetermined descent of the elevator to in- [54] fg fi i tercept and remove a completed stack from the elevator to 8 enable the completed stack to be ejected from the stacker and [52] U.S.Cl 271/88 the elevator reset for the next stack, stack ejector means {5 1] Int. Cl. B65h 31/10 adapted when actuated to move the completed stack along the [50] Field of Search 271/88, 86, stack transfer means and out of the stacker, and control means 80 for the elevator and the ejector means adapted to lower the elevator as a stack builds up thereon, and, following transfer [56] Reierenm CM of the completed stack from the elevator to the transfer UNITED STATES PATENTS means, to actuate the ejector means to remove the completed 2,626,800 1/1953 Martin 271/88 x stack, the Control means including means to quickly return the 1 14g 5o9 915 Gan-[meter 271 0 elevator to the stack-start position following ejection of the 1,087,716 2/1914 Breckenridge 271/86 x completed stack from the stacker.

PATENTEU DEE28 1971 SHEET 1 OF 4 INVENTOR. ALBERT G. ENSKAT ATTORNEY PATENTEDUECZBIQTI 3.630.517

SHEET 2 BF 4 FIG. 2

PATENTEDUEDZBIBYI 3,630,517

- SHEET 3 [1F 4 FIG. 3

COUNTER STACKER This invention relates to an article stacker, and more particularly, to an improved article stacker incorporating a multiple speed stacking elevator with cooperating stack transfer and ejecting means.

In handling articles such as newspapers, magazines, envelopes, and the like, it is frequently desirable to form the articles into stacks. This may occur for example in article labeling or addressing systems, where addressed articles having common Zip Code designations must be bundled together for group mailing in accordance with Post Office regulations. While the articles may of course 'be manually stacked, or stacked through manual stopping and starting of a stacker in accordance with the number of articles in each Zip Code group, such manual stacking or manual stacker is expensive in terms of labor costs and inefficiency in high volume articles addressing systems.

A further aspect inherent in high volume article addressing systems relates to the speed with which articles may be handled. Clearly, the faster the articles are handled, the greater the system efficiency. Normally, rapid article handling involves high article velocities and since the articles themselves have very little inherent rigidity, problems arise at the stacker where the rapidly moving articles must be brought to a stop. The sudden stopping of the rapidly moving articles at the stacker may temporarily buckle the article midportion and/or lift the article trailing edge or edges, either of which may interfere with proper movement of the next succeeding article. This may lead to an article jam which in the high speed article handling system, could be monumental.

It is a principal object of the present invention to provide a new and improved article stacking apparatus.

It is a further object of the present invention to provide an article stacker for use in high speed article handling systems.

It is an object of the present invention to provide an article stacker incorporating means to control article buckling or lifting as may be occasioned by the rapid stopping of the articles on entry into the article stacker.

It is an object of the present invention to provide improved article control means designed to properly position articles on the elevator of an article stacker for stacking.

It is an object of the present invention to provide article controlling means for article stackers adapted to prevent misalignment or jamming of the articles in the stacker.

This invention relates to an article stacking apparatus adapted to accommodate a high speed article input, comprising in combination, an elevator to which the articles are delivered for stacking; article stop means engageable with the articles to stop the relatively rapidly moving articles in position for stacking on the elevator; a pair of spaced upper guides extending in a direction generally longitudinal of the direction of article flow and into partial overlaying relationship with the elevator whereby to restrict upward buckling of the articles on stopping thereof by the article stop means; and means forming an inlet base to the stacking apparatus including a driven guide roller below each of the article guides for contact with the bottom and trailing edges of the articles, the guide rollers being adapted to prevent lifting of the article trailing edges on stopping of the articles by the stop means, and at least one lower guiding member having a first downwardly extending surface portion forming a stationary backstop for the articles, and a second generally horizontally extending surface portion adapted to support articles en route to-the stacking apparatus, the portion of the member between the first and second surface portions being curved with a radius of curvature substantially equal to the radius of curvature of the guide rollers; the guides including a downwardly projecting springlike member adapted to maintain the articles in contact with the guide rollers as the articles pass thereover.

Other objects and advantages will be apparent from the ensuing description and drawings in which:

FIG. I is a schematic representation of an article addressing system incorporating the article stacker of the present invention with the elevator drive chain displaced through from a true position to facilitate explanation;

FIG. 2 is a side view partially in section of the article stacker shown in FIG. 1;

FIG. 3 is a top plan view of the article stacker shown in FIG. 1; and

FIG. 4 is an end view with parts broken away of the article stacker shown in FIG. 1;

Referring particularly to FIG. 1 of the drawings, an article stacker 10 is thereshown incorporated into an article addressing or labeling system 3. Labeling system 3 includes an article feeder 4 of the type shown in copending application, Ser. No. 774,956, filed Nov. l2, I968 in the name of D. W. Watson et al., now U.S. Pat. No. 3,578,3I6 for supplying articles 20, such as magazines, newspapers, envelopes. and the like in seriatim to an addressing machine 5. Articles discharged by feeder 4 pass through a suitable article control means, such as gate 9 and pinch roller pair 11 onto article transport 26 of addressing machine 5. To control the feed of articles 20 to addressing machine 5, article feeder 4 incorporates a solenoid operated disconnect 6 adapted when actuated to move forward into the path of movement of depending drive latch arm 17 causing latch 15 to pivot upwardly and withdraw drive lug 15' thereof from driving slider 19. Slider 19 is conveniently driven through suitable eccentric means (not shown) from addressing machine drive motor 5.

Addressing machine 5 comprises any suitable article labeling or addressing machine such as that described in copending application Ser. No. 653,144, filed July I3, 1967 in the name of R. C. Sheriff, now U.S. Pat. No. 3,532,854. Addressing machine 5 includes a labeling head portion 8 with rotatable label transfer wheel 13 for transferring individual labels or the label information thereon to the articles 20 moving therebelow on article transport 26. Labeling head 8 including transfer wheel 13 is driven by suitable drive means through a suitable electromagnetically controlled clutch (not shown). The operating coil for the labeling head drive clutch is controlled by article sensor 75 arranged above transport 26 to sense the feed of articles to wheel 13. On interruption in the feed of articles to transfer wheel 13, sensor 75 stops head 8 to prevent loss or mutilation of the address labels.

The addressed articles are carried by transport 26 to stacker 10 where, as will appear, the articles are automatically stacked into stacks of predetermined size or quantity. Completed stacks 22 from stacker 10 are ejected therefrom by ejector 16 onto stack discharge conveyor 24 for removal from the system 3. A suitable article counter 76, is provided to count the articles processed. Conveniently, article sensor 75 is utilized to provide the input signal to counter 76.

Referring particularly to FIG. 2 of the drawings article stacker 10 includes stacking elevator 12, stack interceptor l4, stack ejector 16, and stack height control 18. As will appear more fully herein, stacker 10 is adapted to form articles 20, which may comprise envelopes, newspapers and the like, into stacks 22 of predetermined height and/or quantity. The completed stacks 22 are removed by means of stack discharge conveyor 24.

Article stacker 10 includes a base 30 having upstanding bearing bars 31 upon which carriage 32 of elevator 12 is journaled for vertical movement. Elevator carriage 32 carries a plurality of horizontally extending, spaced apart bars 34 thereon which cooperate to form the base or floor upon which articles 20 being stacked rest.

Elevator carriage 32 is secured to vertical driving chain 36 carried by upper and lower sprockets 37, 38. Sprocket shafts 37', 38' are joumaled on rear frame member 35. Sprocket shaft 38' is suitably driven by two speed motor 41 through transmission 42. Transmission 42 includes a suitable electromagnetically operated clutch 73 effective when engaged to couple chain 36 with motor 41 and an electromagnetically controlled brake 74 effective when engaged to hold elevator 12 against movement, the clutch 73 being normally disengaged while brake 74 is normally engaged so that energization of the operating coils therefor engages clutch 73 and releases brake 74.

Elevator 12 is lowered at low speed during stacking and is reset to the stack-start position of FIG. 1 at high speed. Elevator control switches 92, 94, 102, 109 are arranged along the path of movement of elevator 12.

Stacker has upstanding sides 50 supported on base 30 to prevent the articles from falling off elevator 12 during stacking. A suitable stop 51 is provided to limit forward movement of articles 20.

Stack height control 18 includes a control ski 55 pivotally suspended above elevator 12 on arm 56v Arm 56 is in turn secured to switch base 65 suitably supported in side members 54. Side members 54 are carried on rotatable cross-shaft 59 journaled in the upstanding stacker sides 50. An abutment 53 limits downward swinging movement of the height control 18 about cross-shaft 59. Preferably, side members 54 have a longitudinally extending slotlike opening 66 therein to enable the position of height control 18 to be adjusted in correspondence with the length of the articles 20 being handled.

A switch control arm 60 is pivotally attached to the opposite end of arm 56 above elevator start and stop switches 62, 63 on base 65. A suitable switch operating cam 61 is mounted on the lower end of control arm 60 in operative relation with switches 62, 63.

A control link 58 is pinned between the upstanding support base 57 of ski 55 and switch control arm 60 such that swinging movement of ski 55 results in corresponding swinging movement of control arm 60. A suitable biasing spring 64 is provided to bias control link 58 in the direction shown by the solid line arrow and ski 55 in a counterclockwise direction. Suitable stop means (not shown) are provided to limit swinging movement ofski 55.

As can be understood, the weight of height control 18 normally serves to maintain the control 18 in the position shown against abutment 53. Where a malfunction in labeling system 3 results in an unwarranted increase in the height of articles 20 on elevator 12, height control 18 is forced upwardly in a counterclockwise direction about cross-shaft 59. To protect the labeling system 3 against malfunctions of this type, stop switch 120 is provided. Switch 120 is arranged so that preset raising movement of stack height control 18 actuates switch 120 and shuts down labeling system 3.

As can be appreciated, articles 20 discharged onto elevator 12 by article transport 26 slide or skid across the surface of bars 34, or the topmost article resting thereon, under ski 55 and into abutment with article stop 51. As the height of the article stack on elevator 20 rises, ski 55 is turned in a counterclockwise direction to displace control link 58 in the direction shown by the dotted line arrow in FIG. 2. On predetermined movement of control link 58, switch control cam 61 closes elevator start switch 62 to engage clutch 73 and release brake 74 to move elevator 12 downwardly at low speed. As elevator 12 descends and the effective height of the article stack thereon decreases, ski 55 pivots in a clockwise direction with concurrent movement of control link 58 in the direction shown by the solid line arrow. Following predetermined displacement of control link 58, cam 61 opens switch 63 to disengage clutch 73 while engaging brake 74.

To remove the completed stack of articles on elevator 12, stack interceptor l4 and ejector 16 are provided. Interceptor 14 comprises a plurality of stationary, spaced horizontal support bars 43 arranged in the path of movement of elevator 12 at a level substantially the same as or slightly above the operating surface of stack discharge conveyor 24. The relative spacing between the elevator bars 34 and interceptor bars 43 is such that bars 34 are able to pass between bars 43 to enable elevator 12 to descend below interceptor 14 and transfer the stack of articles on elevator 12 onto interceptor l4. Stack interceptor bars 43 are suitably supported by stacker base 30.

It is understood that suitable adjusting means (not shown) may be provided to permit the height of stack interceptor 34 to be varied to match the height of discharge conveyor 24.

Stack ejector 16 comprises a plurality of spaced, upstanding bars 44 supported on carriage 45. Ejector carriage 45 is carried by a pair of spaced, horizontal journals 46 for movement toward and away from discharge conveyor 24. Ejector bars 44 are offset relative to elevator bars 34 and interceptor bars 43 to permit relative movement of elevator 12 and ejector 16 between each other and interceptor l4.

Ejector carriage 45 is attached to drive chain 47. Chain 47 is carried by sprockets 48 suitably joumaled on frame 30. Ejector drive motor 49 is connected to sprocket 48 by belt 52. Ejector control switches 98, 99 are arranged along the path of movement of carriage 45 for actuation thereby, switch 98 being operated by ejector carriage 45 when ejector 16 is in the ready or start position shown in the drawings.

Stack discharge conveyor 24 comprises one or more endless belts 68 stretched across suitable support rollers 69. Conveyor 24, which is driven by motor 70, is disposed at substantially the same operative level or slightly below that of stack interceptor 14. Conveyor 24 is normally operated continuously, control switch 126 serving to stop conveyor 24 on failure of the operator to remove a completed stack therefrom.

As may be understood, article feeder 4 feeds articles 20 to be addressed forward one at a time through gate 9 and pinch roller pair 11 onto article transport 26 of addressing machine 5. Transport 26 brings the unaddressed articles to label transfer wheel 13 where individual addresses are transferred to each article. The addressed articles leaving transfer wheel 13 on transport 26 are discharged one by one onto elevator 12 of stacker 10, the articles sliding underneath ski 55 and coming to rest with their leading edges against article stop 51.

As the stack of articles 20 on elevator 12 builds up, contact of each succeeding article with ski 55 causes ski 55 to swing in a counterclockwise direction against the bias of spring 64. Following predetermined swinging movement of ski 55, representing a predetermined stack height, switch control cam 61 thereof closes elevator start switch 62 to engage elevator clutch 73 and release elevator brake 74.

On engagement, clutch 73 couples elevator drive motor 41 with chain drive sprocket 38 to move elevator 12 downwardly at low speed.

As elevator 12 descends, the level of the stack of articles thereon falls, the rate of feed of articles 20 to stacker 10 by transport 26 being less than the speed at which elevator 20 descends. Ski 55, under the influence of spring 64, accordingly swings back in a clockwise direction. Following predetermined movement of ski 55 in a clockwise direction, switch cam 61 opens elevator stop switch 63 to disengage clutch 73 and apply brake. Elevator 12 is accordingly stopped and held in a stationary position. It is understood that the continued feed of labeled articles 20 onto elevator 12 with resulting increase in article stack size results in intermittent lowering of elevator 12 under the control of ski 55 in the manner described.

Counter 76 serves to control labeling system 3 including stacker 10 in accordance with the program setting thereof to provide stacks each comprised of a predetermined number of articles. On reaching the predetermined article count, on a signal from counter 76, the armature of solenoid 6 is interposed in the path of movement of depending latch arm 17 to uncouple latch 15 from slider 19 and stop feeder 4. At the same time, initiation of the stacker ejecting cycle is delayed until articles left on transport 26 following stopping of article feeder 4 reach stacker 10.

[t is understood that, following stopping of article feeder 4, sensor responds to the interruption in the flow of articles to addressing machine 5, to stop labeling head 8.

Following the requisite delay, elevator drive motor 41 is accordingly switched from low to high speed.

At the same time, clutch 73 is engaged while brake 74 is released. Elevator 12 therefore descends at high speed.

As elevator 12 descends, elevator support bars 34 pass between and through bars 43 of stack interceptor 14 and the stack 22 of addressed articles on elevator 12 is transferred from elevator 12 onto interceptor l4.

As elevator 12 moves through interceptor l4, carriage 32 starts ejector drive motor 49 and, following a preset interval,

energizes solenoid 6 to reengage drive latch 15 and restart ar ticle feeder 4. V

Ejector motor 49 drives ejector 16 forward (in the direction of the solid line arrow), to bring the upstanding bars 44 thereof into contact with the rear of the article stack resting on interceptor 14 to slide the-stack along interceptor bars 43 and onto discharge conveyor 24. Conveyor 24 carries the finished stack away.

With initial movement of ejector 14 forward, ejector reset switch 98 closes to maintain ejector motor 49 operative. As ejector 14 nears article discharge conveyor 24, the ejector carriage 45 momentarily closes elevator reset switch 99 to engage clutch 86 and release brake 87 whereby elevator 12 moves upwardly at high speed.

Ejector drive motor 49 carries the ejector 14 back toward the ejector start position shown in the drawings. As ejector 14 reaches the ejector start position, the ejector carriage 45 opens ejector reset switch 98 to stop ejector motor 49.

As elevator 12 nears the top of stacker 10, and thereafter begins to descend, elevator motor 41 is switched from high speed to low speed. Elevator 12 descends until elevator stop switch 63, which is controlled by the position of ski 55, opens to disengage clutch 73 while engaging brake 74 to stop elevator l2. Stacker 10 is now ready for the next stacking cycle.

Where during the operation of stacker 10, the input of articles thereto is such that elevator 12, under the control of ski 55, descends to a point where elevator 12 closes ejector start switch 94 before the predetermined article count is reached, switch 94 shuts down stacker 10.

Should an article jam occur on elevator 12, the rapid buildup in the article level height would overcome the normal low speed descent of elevator 12 under the control of stack height responsive ski 55 as described heretofore, and the supply of articles to elevator 12 would swing the entire stack height control assembly 18 upwardly in a counterclockwise direction about cross shaft 59. As control assembly 18 lifts, system stop switch 120 is opened to interrupt power to the system control circuit to thereby shutdown the various operating components of addressing system 3 pending removal of the article jam.

To promote efficient labeling system operation, the system components such as article feeder 4 and addressing machine 5 are normally operated at relatively high speeds. Addressed articles 20 leaving article conveyor 26 therefore enter stacker 10 at relatively high velocities, the articles sliding across the top of elevator 12 or thelast article thereon, underneath ski 55 and into abutment with stop 51. Where the articles are relatively flexible, for example newspapers, the abrupt stopping of the article leading edge on contact with article stop 51 may cause the midportion of the article to buckle or collapse upwardly as the velocity of the trailing portions of the articles is absorbed. With discharge of the articles from conveyor 26 into stacker 10 one after the other, the next succeeding article may strike the buckled portion of the preceding article with the result that feeding of the second article may be incomplete or the article may be diverted an an article jam may occur.

Where the articles 20 comprise multipage items, such as newspapers, the articles are normally fed folded edge first with the loose edges trailing. Should articles of this type buckle in the manner described, subsequent collapse of the buckle often results in the trailing edges momentarily raising or snapping upwardly into the path of the next succeeding article so that the leading edge of the next article drives or curls the raised trailing edge of the previous article over, folding the first article upon itself. In addition, this may result in incomplete or abortive feeding of the second article with the possibility of an article jam.

To control the rapidly moving articles as they are discharged onto elevator 12 from conveyor 26 and prevent incomplete feeding, misalignment, or folding of the articles there is provided, adjacent the inside edge of stacker 10, a pair of spaced guide rollers 150. Rollers 150 are supported on drive shaft 153. Shaft 153 is driven by suitable means (not shown) such that guide rollers rotate at approximately the same speed as article conveyor 26.

A plurality of spaced generally right angle guides 155 are provided across the inlet to stacker 10 between and on the sides of guide rollers 150. Guides 155 include a curved portion 172 between legs 170, 171 thereof. The radius of curvature of curved portion 172 is preferably substantially equal to the radius of curvature of guide rollers 150. Guides are arranged so that the horizontal and vertical leg portions 170, 171 thereof are substantially level with or slightly below the periphery of guide rollers 150. As will appear, rollers 150 and guides cooperate to guide the articles onto elevator 12, rollers 150 providing a downward thrust on the article trailing edge or edges to seat the articles on the elevator and forestall any tendency of the articles to lift or raise up on stopping thereof while guides 155 assist in supporting the articles as they enter stacker 10 and serve as a backstop for articles on elevator 12.

A plurality of spaced longitudinally extending and downwardly inclined guide strips 156 are supported above the discharge end of conveyor 12 by suitable means (not shown). The terminal ends 157 of guide strips 156 project into stacker 10 and over elevator 12, the space between guide strips 156 and rollers 150 and guides 155 therebelow forming a throatlike passage 158 through which articles 20 pass from conveyor 26 onto stacker elevator 12. Suitable means (not shown) may be provided to vary the angle of inclination and amount of projection of guide strip ends 157 into stacker 10;

While the number and arrangement of guide strips 156 may be tailored to the type of articles being handled, for example newspapers, at least one guide strip 156 is provided opposite each guide roller 150. Guides 156' have a slotlike aperture 160 therein through which spring member 162 projects. Spring members 162 are supported on guides 156, members 162 being suitably configured to provide a downwardly projecting free end portion 163 which extends through guide aperture 160 into relatively light pressure contact with the surface of the guide roller 150 therebelow. Suitable means such as finger screw 164 are provided to adjust the downward bias of members 162.

Articles 20 discharging from conveyor 26 pass underneath guide strips 156 and between the nip formed by guide rollers 150 and ends 163 of spring members 162. The projecting ends 157 of guide strips 156, which are normally slightly above the level of the document stack depending upon the position of elevator 12 and the height of the article stack thereon, limit or control the size and height of the buckle that may be formed in the article as the article leading edge strikes stop 51. It is understood that the control response of height control ski 55 is arranged to enhance operation of guide strips 156. For example, should the stop control switch 63 setting permit the elevator 12 to descend too great a distance, the effectiveness of guides 156 in preventing article buckling could be impeded and therefore the interaction of guide strips 156 with control ski 55 is closely correlated.

During stacking, spring members 162 serve to maintain the entering articles, particularly the trailing edge portion thereof, in driving contact with guide rollers 150 to assure rollers 150 imparting a downward impetus to the article trailing edge or edges as the article passes thereover. This obviates, in cooperation with guide strips 156, the tendency of the article trailing edge or edges to rise upwardly as the article is brought to an abrupt stop on elevator 12.

It is also understood that in the event of a stacker malfunction, for example, failure of elevator 12 to descend in accordance with the buildup of stack height or premature ascent of elevator 12 with articles stacked thereon, will also trip stop switch 120 as described above to shutdown addressing system 3.

While the invention has been described with reference to the structure disclosed herein, it is not confined to the details set forth; but is intended to cover such modifications or changes as may come within the scope of the following claims.

What is claimed is: 1. In an article stacking apparatus adapted to accommodate a high speed article input, said stacking apparatus including an elevator to which said articles are delivered for stacking, and article stop means engageable with the articles to stop the relatively rapidly moving articles in position for stacking on said elevator, the combination of:

means forming an inlet base to said stacking apparatus including a pair of driven guide rollers adapted to contact the bottom and trailing edges of said articles. said guide rollers being adapted to prevent lifting of said article trailing edges on stopping of said articles by said stop means; and at least one lower guiding member having a first downwardly extending surface portion forming a stationary backstop for said articles, and a second generally horizontal extending surface portion adapted to support articles en route to said stacking apparatus, the portion of said member between said first and second surface portions being curved with a radius of curvature substantially equal to the radius of curvature of said guide rollers; and

an upper guide above each of said driven guide rollers, said upper guides extending in a direction generally longitudinal of the direction of article flow and into partial overlaying relationship with said elevator downstream of said guide rollers whereby to restrict upward buckling of said articles on said elevator on stopping thereof by said article stop means;

said guides including a downwardly projecting springlike member adapted to maintain said articles in contact with said guide rollers as said articles pass thereover.

2. The article stacking apparatus according to claim 1 in which said guides are slanted downwardly toward said stacking apparatus elevator to form in cooperation with said guide rollers and said lower guiding member a progressively narrowing article inlet to said elevator.

3. The article stacking apparatus according to claim I in which said lower guiding member comprises a plurality of wirelike elements spacedly positioned across the width of said article inlet. 

1. In an article stacking apparatus adapted to accommodate a high speed article input, said stacking apparatus including an elevator to which said articles are delivered for stacking, and article stop means engageable with the articles to stop the relatively rapidly moving articles in position for stacking on said elevator, the combination of: means forming an inlet base to said stacking apparatus including a pair of driven guide rollers adapted to contact the bottom and trailing edges of said articles, said guide rollers being adapted to prevent lifting of said article trailing edges on stopping of said articles by said stop means; and at least one lower guiding member having a first downwardly extending surface portion forming a stationary backstop for said articles, and a second generally horizontal extending surface portion adapted to support articles en route to said stacking apparatus, the portion of said member between said first and Second surface portions being curved with a radius of curvature substantially equal to the radius of curvature of said guide rollers; and an upper guide above each of said driven guide rollers, said upper guides extending in a direction generally longitudinal of the direction of article flow and into partial overlaying relationship with said elevator downstream of said guide rollers whereby to restrict upward buckling of said articles on said elevator on stopping thereof by said article stop means; said guides including a downwardly projecting springlike member adapted to maintain said articles in contact with said guide rollers as said articles pass thereover.
 2. The article stacking apparatus according to claim 1 in which said guides are slanted downwardly toward said stacking apparatus elevator to form in cooperation with said guide rollers and said lower guiding member a progressively narrowing article inlet to said elevator.
 3. The article stacking apparatus according to claim 1 in which said lower guiding member comprises a plurality of wirelike elements spacedly positioned across the width of said article inlet. 